St Kentigern College will host Otago Boys High in the national 1st XV top four grand final in Auckland next Saturday after clinically dispatching Hamilton Boys' High School 29-13 in a national top-four semifinal at Rotorua Boys' High School yesterday.

St Kentigern's superior forward power meant set-piece dominance was established midway through the first half, which resulted in four outstanding tries.

For the first time since 2001, two unbeaten schools will contest the final after Otago Boys' High School rallied from 16-3 down to beat Napier Boys' High 30-16.

The Kelston-Hamilton match started in predictably cagey fashion but once the teams settled, it was St Kentigern who made the first breakthrough. A long sequence of attack, involving a sharp 20-metre break by halfback Sam Nock and good continuity by the whole team, resulted in hooker Matthew Morrison rumbling over, and it was 5-0 to St Kents.

Hamilton responded swiftly when wing Mikaere Beattie stepped past three defenders to scurry in under the posts, after a similarly long buildup by Hamilton.

Bryn Gatland converted for a short-lived 7-5 Hamilton lead.

But from the kickoff, St Kents' Fijian flyer Suliasi Vunivalu snatched the ball on the full and flashed 40m to score a spectacular try, regaining a lead that St Kents never looked like losing.

Lock Jack Fallon scored just before halftime and Nock late in the second half as St Kentigern's strangled Hamilton into submission.

Hamilton's season ends with them as Super 8 champions and winners of 17 out of 20 games.

As they did in the South Island final, Otago Boys High struggled to make an impression in the first half but roared back to life with 27 unanswered points in 20 minutes to reach the final for the first time since 1998.

The turning point in the game came when blindside flanker Josh Dickson thundered in between the posts after receiving a Troy Callander offload close to the line. Dickson has played four games shown on the Rugby Channel this year and scored a try in every one of them

After being outplayed in the first half, Otago found themselves down 16-10, then rediscovered their best form and scored two long-range tries.

Ben Miller scored the team's 200th try of the season after he stretched out in the corner following a bust by Aleki Morris, and then Morris scored himself after pushing past some meek defence.

Earlier, Napier had played a smart and expansive game to out- hustle Otago. Fullback Sam McNicol and second-five Jesse Paewai broke the line frequently with strong, direct running as Napier built constant pressure.

But this season, when Otago get on a roll they are close to unstoppable. Dickson, No 8 Alex Fitzgerald, captain and halfback Josh Renton, with his long and accurate passing, and Morris in particular are as good as any school players in the country.